/* -------------------------------------------------------------------------
 *
 * primnodes.h
 *	  Definitions for "primitive" node types, those that are used in more
 *	  than one of the parse/plan/execute stages of the query pipeline.
 *	  Currently, these are mostly nodes for executable expressions
 *	  and join trees.
 *
 *
 * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 * Portions Copyright (c) 2010-2012 Postgres-XC Development Group
 * Portions Copyright (c) 2021, openGauss Contributors
 *
 * src/include/nodes/primnodes.h
 *
 * -------------------------------------------------------------------------
 */
#ifndef PRIMNODES_H
#define PRIMNODES_H

#include "access/attnum.h"
#include "nodes/pg_list.h"
#include "nodes/params.h"
#include "db4ai/db4ai.h"

/* ----------------------------------------------------------------
 *						node definitions
 * ----------------------------------------------------------------
 */

/*
 * Alias -
 *	  specifies an alias for a range variable; the alias might also
 *	  specify renaming of columns within the table.
 *
 * Note: colnames is a list of Value nodes (always strings).  In Alias structs
 * associated with RTEs, there may be entries corresponding to dropped
 * columns; these are normally empty strings ("").	See parsenodes.h for info.
 */
typedef struct Alias {
    NodeTag type;
    char* aliasname; /* aliased rel name (never qualified) */
    List* colnames;  /* optional list of column aliases */
} Alias;

typedef enum InhOption {
    INH_NO,     /* Do NOT scan child tables */
    INH_YES,    /* DO scan child tables */
    INH_DEFAULT /* Use current SQL_inheritance option */
} InhOption;

/* What to do at commit time for temporary relations */
typedef enum OnCommitAction {
    ONCOMMIT_NOOP,          /* No ON COMMIT clause (do nothing) */
    ONCOMMIT_PRESERVE_ROWS, /* ON COMMIT PRESERVE ROWS (do nothing) */
    ONCOMMIT_DELETE_ROWS,   /* ON COMMIT DELETE ROWS */
    ONCOMMIT_DROP           /* ON COMMIT DROP */
} OnCommitAction;

// If enable_compress is off, the table will not be compressed no matter
// which option is specified.
//
typedef enum OptCompress {
    COMPRESS_NO = 0,
    COMPRESS_LOW,
    COMPRESS_MIDDLE,
    COMPRESS_HIGH,
} OptCompress;

/* How to handle rows that duplicate unique key values */
typedef enum OnDuplicateAction {
    DUPLICATE_ERROR = 0,
    DUPLICATE_IGNORE,
    DUPLICATE_REPLACE
} OnDuplicate;

/*
 * RangeVar - range variable, used in FROM clauses
 *
 * Also used to represent table names in utility statements; there, the alias
 * field is not used, and inhOpt shows whether to apply the operation
 * recursively to child tables.  In some contexts it is also useful to carry
 * a TEMP table indication here.
 */
typedef struct RangeVar {
    NodeTag type;
    char* catalogname;   /* the catalog (database) name, or NULL */
    char* schemaname;    /* the schema name, or NULL */
    char* relname;       /* the relation/sequence name */
    char* partitionname; /* partition name, if is a partition */
    char* subpartitionname; /* partition name, if is a subpartition */
    InhOption inhOpt;    /* expand rel by inheritance? recursively act
                          * on children? */
    char relpersistence; /* see RELPERSISTENCE_* in pg_class.h */
    Alias* alias;        /* table alias & optional column aliases */
    int location;        /* token location, or -1 if unknown */
    bool ispartition;    /* for partition action */
    bool issubpartition;    /* for subpartition action */
    List* partitionKeyValuesList;
    bool isbucket;       /* is the RangeVar means a hash bucket id ? */
    List* buckets;       /* the corresponding bucketid list */
    int length;
#ifdef ENABLE_MOT
    Oid foreignOid;
#endif
    bool withVerExpr;
    List* partitionNameList; /* for FROM table PARTITION (p1, subp2, ...) clause */
    List* indexhints;        /* a list of b mode index hint indexHintDefinition members */
} RangeVar;

/*
 * IntoClause - target information for SELECT INTO, CREATE TABLE AS, and
 * CREATE MATERIALIZED VIEW
 */
typedef struct IntoClause {
    NodeTag type;

    RangeVar* rel;           /* target relation name */
    List* colNames;          /* column names to assign, or NIL */
    List* options;           /* options from WITH clause */
    OnCommitAction onCommit; /* what do we do at COMMIT? */
    int8 row_compress;       /* row compression flag */
    char* tableSpaceName;    /* table space to use, or NULL */
    bool skipData;           /* true for WITH NO DATA */
    bool ivm;                /* true for WITH IVM */
    char relkind;            /* RELKIND_RELATION or RELKIND_MATVIEW */
    List* userVarList;       /* user define variables list */
    List* copyOption;        /* copyOption for select...into statement */
    char* filename;          /* filename for select...into statement */
    bool is_outfile;         /* true for outfile */
#ifdef PGXC
    struct DistributeBy* distributeby; /* distribution to use, or NULL */
    struct PGXCSubCluster* subcluster; /* subcluster node members */
#endif
    List* tableElts;         /* column definitions(list of ColumnDef) */
    Node *autoIncStart; /* DefElem for AUTO_INCREMENT = value*/
    OnDuplicateAction onduplicate;     /* how to handle rows that duplicate unique key values */
} IntoClause;

/* ----------------------------------------------------------------
 *					node types for executable expressions
 * ----------------------------------------------------------------
 */

/*
 * Expr - generic superclass for executable-expression nodes
 *
 * All node types that are used in executable expression trees should derive
 * from Expr (that is, have Expr as their first field).  Since Expr only
 * contains NodeTag, this is a formality, but it is an easy form of
 * documentation.  See also the ExprState node types in execnodes.h.
 */
typedef struct Expr {
    NodeTag type;
    double selec;
} Expr;

/*
 * Var - expression node representing a variable (ie, a table column)
 *
 * Note: during parsing/planning, varnoold/varoattno are always just copies
 * of varno/varattno.  At the tail end of planning, Var nodes appearing in
 * upper-level plan nodes are reassigned to point to the outputs of their
 * subplans; for example, in a join node varno becomes INNER_VAR or OUTER_VAR
 * and varattno becomes the index of the proper element of that subplan's
 * target list.  But varnoold/varoattno continue to hold the original values.
 * The code doesn't really need varnoold/varoattno, but they are very useful
 * for debugging and interpreting completed plans, so we keep them around.
 */
#define INNER_VAR 65000     /* reference to inner subplan */
#define OUTER_VAR 65001     /* reference to outer subplan */
#define INDEX_VAR 65002     /* reference to index column */
#define MERGEJOIN_VAR 65003 /* reference to merge join results */

#define IS_SPECIAL_VARNO(varno) ((varno) >= INNER_VAR)

/* Symbols for the indexes of the special RTE entries in rules */
#define PRS2_OLD_VARNO 1
#define PRS2_NEW_VARNO 2

typedef struct Var {
    Expr xpr;
    Index varno;          /* index of this var's relation in the range
                           * table, or INNER_VAR/OUTER_VAR/INDEX_VAR */
    AttrNumber varattno;  /* attribute number of this var, or zero for
                           * all */
    Oid vartype;          /* pg_type OID for the type of this var */
    int32 vartypmod;      /* pg_attribute typmod value */
    Oid varcollid;        /* OID of collation, or InvalidOid if none */
    Index varlevelsup;    /* for subquery variables referencing outer
                           * relations; 0 in a normal var, >0 means N
                           * levels up */
    Index varnoold;       /* original value of varno, for debugging */
    AttrNumber varoattno; /* original value of varattno */
    int location;         /* token location, or -1 if unknown */
} Var;

/*
 * Const
 */
typedef struct Const {
    Expr xpr;
    Oid consttype;     /* pg_type OID of the constant's datatype */
    int32 consttypmod; /* typmod value, if any */
    Oid constcollid;   /* OID of collation, or InvalidOid if none */
    int constlen;      /* typlen of the constant's datatype */
    Datum constvalue;  /* the constant's value */
    bool constisnull;  /* whether the constant is null (if true,
                        * constvalue is undefined) */
    bool constbyval;   /* whether this datatype is passed by value.
                        * If true, then all the information is stored
                        * in the Datum. If false, then the Datum
                        * contains a pointer to the information. */
    int location;      /* token location, or -1 if unknown */
    bool ismaxvalue;   /*is the Const represent maxValue, maxValue is used for partition */

    Cursor_Data cursor_data;
} Const;

/* ----------------
 * Param
 *		paramkind - specifies the kind of parameter. The possible values
 *		for this field are:
 *
 *		PARAM_EXTERN:  The parameter value is supplied from outside the plan.
 *				Such parameters are numbered from 1 to n.
 *
 *		PARAM_EXEC:  The parameter is an internal executor parameter, used
 *				for passing values into and out of sub-queries or from
 *				nestloop joins to their inner scans.
 *				For historical reasons, such parameters are numbered from 0.
 *				These numbers are independent of PARAM_EXTERN numbers.
 *
 *		PARAM_SUBLINK:	The parameter represents an output column of a SubLink
 *				node's sub-select.  The column number is contained in the
 *				`paramid' field.  (This type of Param is converted to
 *				PARAM_EXEC during planning.)
 *
 * Note: currently, paramtypmod is valid for PARAM_SUBLINK Params, and for
 * PARAM_EXEC Params generated from them; it is always -1 for PARAM_EXTERN
 * params, since the APIs that supply values for such parameters don't carry
 * any typmod info.
 * ----------------
 */
typedef enum ParamKind { PARAM_EXTERN, PARAM_EXEC, PARAM_SUBLINK } ParamKind;

typedef struct Param {
    Expr xpr;
    ParamKind paramkind; /* kind of parameter. See above */
    int paramid;         /* numeric ID for parameter */
    Oid paramtype;       /* pg_type OID of parameter's datatype */
    int32 paramtypmod;   /* typmod value, if known */
    Oid paramcollid;     /* OID of collation, or InvalidOid if none */
    int location;        /* token location, or -1 if unknown */
    Oid tableOfIndexType; /* type Oid of table of (wait to discard) */
    Oid recordVarTypOid; /* package record var's composite type oid */
    List* tableOfIndexTypeList; /* type Oid list of table of, max size 6 */
    bool is_bind_param;
    char* name;
    bool is_pkg_var;
    List* args;
} Param;

/*
 * Aggref
 *
 * The aggregate's args list is a targetlist, ie, a list of TargetEntry nodes
 * (before Postgres 9.0 it was just bare expressions).	The non-resjunk TLEs
 * represent the aggregate's regular arguments (if any) and resjunk TLEs can
 * be added at the end to represent ORDER BY expressions that are not also
 * arguments.  As in a top-level Query, the TLEs can be marked with
 * ressortgroupref indexes to let them be referenced by SortGroupClause
 * entries in the aggorder and/or aggdistinct lists.  This represents ORDER BY
 * and DISTINCT operations to be applied to the aggregate input rows before
 * they are passed to the transition function.	The grammar only allows a
 * simple "DISTINCT" specifier for the arguments, but we use the full
 * query-level representation to allow more code sharing.
 */
typedef struct Aggref {
    Expr xpr;
    Oid aggfnoid;    /* pg_proc Oid of the aggregate */
    Oid aggtype;     /* type Oid of result of the aggregate */
    Oid aggcollid;   /* OID of collation of result */
    Oid inputcollid; /* OID of collation that function should use */
#ifdef PGXC
    Oid aggtrantype;       /* type Oid of transition results */
    bool agghas_collectfn; /* is collection function available */
    int8 aggstage;         /* in which stage this aggref is in */
#endif                     /* PGXC */
#ifdef USE_SPQ
    AggSplit aggsplittype;  /* expected agg-splitting mode of parent Agg */
#endif
    List* aggdirectargs;   /* direct arguments, if an ordered-set agg */
    List* args;            /* arguments and sort expressions */
    List* aggorder;        /* ORDER BY (list of SortGroupClause) */
    List* aggdistinct;     /* DISTINCT (list of SortGroupClause) */
    bool aggiskeep;
    bool aggkpfirst;
    bool aggstar;          /* TRUE if argument list was really '*' */
    bool aggvariadic;      /* true if variadic arguments have been
                            * combined into an array last argument */
    char aggkind;          /* aggregate kind (see pg_aggregate.h) */
    Index agglevelsup;     /* > 0 if agg belongs to outer query */
    int location;          /* token location, or -1 if unknown */
    List* aggargtypes;     /* type Oids of direct and aggregated args */
    int aggsplit;          /* expected agg-splitting mode of parent Agg */
    Oid aggtranstype;      /* type Oid of aggregate's transition value */
    Expr *aggfilter;       /* FILTER expression, if any */
} Aggref;

/*
 * GroupingFunc
 *
 * A GroupingFunc is a GROUPING(...) expression, which behaves in many ways
 * like an aggregate function (e.g. it "belongs" to a specific query level,
 * which might not be the one immediately containing it), but also differs in
 * an important respect: it never evaluates its arguments, they merely
 * designate expressions from the GROUP BY clause of the query level to which
 * it belongs.
 *
 * The spec defines the evaluation of GROUPING() purely by syntactic
 * replacement, but we make it a real expression for optimization purposes so
 * that one Agg node can handle multiple grouping sets at once.  Evaluating the
 * result only needs the column positions to check against the grouping set
 * being projected.  However, for EXPLAIN to produce meaningful output, we have
 * to keep the original expressions around, since expression deparse does not
 * give us any feasible way to get at the GROUP BY clause.
 *
 * Also, we treat two GroupingFunc nodes as equal if they have equal arguments
 * lists and agglevelsup, without comparing the refs and cols annotations.
 *
 * In raw parse output we have only the args list; parse analysis fills in the
 * refs list, and the planner fills in the cols list.
 */
typedef struct GroupingFunc {
    Expr xpr;
    List* args;        /* arguments, not evaluated but kept for
                        * benefit of EXPLAIN etc. */
    List* refs;        /* ressortgrouprefs of arguments */
    List* cols;        /* actual column positions set by planner */
    Index agglevelsup; /* same as Aggref.agglevelsup */
    int location;      /* token location */
} GroupingFunc;

typedef struct GroupingId {
    Expr xpr;
} GroupingId;

/*
 * WindowFunc
 */
typedef struct WindowFunc {
    Expr xpr;
    Oid winfnoid;    /* pg_proc Oid of the function */
    Oid wintype;     /* type Oid of result of the window function */
    Oid wincollid;   /* OID of collation of result */
    Oid inputcollid; /* OID of collation that function should use */
    List* args;      /* arguments to the window function */
    Index winref;    /* index of associated WindowClause */
    bool winstar;    /* TRUE if argument list was really '*' */
    bool winagg;     /* is function a simple aggregate? */
    int location;    /* token location, or -1 if unknown */
    List* keep_args;
    List* winkporder;
    bool winkpfirst;
#ifdef USE_SPQ
    bool windistinct;	/* TRUE if it's agg(DISTINCT ...) */
#endif
    bool is_from_last;      /* used for window function nth_value */
    bool is_ignore_nulls;   /* used for window function nth_value */
} WindowFunc;

/*
 * pseudo-column "ROWNUM"
 */
typedef struct Rownum {
    Expr xpr;
    Oid  rownumcollid;  /* OID of collation of result */
    int  location;      /* token location, or -1 if unknown */
} Rownum;

typedef struct PriorExpr {
    Expr xpr;
    Node *node;
} PriorExpr;

/* ----------------
 *	ArrayRef: describes an array subscripting operation
 *
 * An ArrayRef can describe fetching a single element from an array,
 * fetching a subarray (array slice), storing a single element into
 * an array, or storing a slice.  The "store" cases work with an
 * initial array value and a source value that is inserted into the
 * appropriate part of the array; the result of the operation is an
 * entire new modified array value.
 *
 * If reflowerindexpr = NIL, then we are fetching or storing a single array
 * element at the subscripts given by refupperindexpr.	Otherwise we are
 * fetching or storing an array slice, that is a rectangular subarray
 * with lower and upper bounds given by the index expressions.
 * reflowerindexpr must be the same length as refupperindexpr when it
 * is not NIL.
 *
 * Note: the result datatype is the element type when fetching a single
 * element; but it is the array type when doing subarray fetch or either
 * type of store.
 * ----------------
 */
typedef struct ArrayRef {
    Expr xpr;
    Oid refarraytype;      /* type of the array proper */
    Oid refelemtype;       /* type of the array elements */
    int32 reftypmod;       /* typmod of the array (and elements too) */
    Oid refcollid;         /* OID of collation, or InvalidOid if none */
    List* refupperindexpr; /* expressions that evaluate to upper array
                            * indexes */
    List* reflowerindexpr; /* expressions that evaluate to lower array
                            * indexes */
    Expr* refexpr;         /* the expression that evaluates to an array
                            * value */
    Expr* refassgnexpr;    /* expression for the source value, or NULL if
                            * fetch */
} ArrayRef;

/*
 * CoercionContext - distinguishes the allowed set of type casts
 *
 * NB: ordering of the alternatives is significant; later (larger) values
 * allow more casts than earlier ones.
 */
typedef enum CoercionContext {
    COERCION_IMPLICIT,   /* coercion in context of expression */
    COERCION_ASSIGNMENT, /* coercion in context of assignment */
    COERCION_EXPLICIT,    /* explicit cast operation */
    
    COERCION_UNKNOWN = 0xFFFFFFFE      /* unknown */
} CoercionContext;

/*
 * CoercionForm - information showing how to display a function-call node
 *
 * NB: equal() ignores CoercionForm fields, therefore this *must* not carry
 * any semantically significant information.  We need that behavior so that
 * the planner will consider equivalent implicit and explicit casts to be
 * equivalent.  In cases where those actually behave differently, the coercion
 * function's arguments will be different.
 */
typedef enum CoercionForm {
    COERCE_EXPLICIT_CALL, /* display as a function call */
    COERCE_EXPLICIT_CAST, /* display as an explicit cast */
    COERCE_IMPLICIT_CAST, /* implicit cast, so hide it */
    COERCE_DONTCARE       /* special case for planner */
} CoercionForm;

/*
 * FuncExpr - expression node for a function call
 */
typedef struct FuncExpr {
    Expr xpr;
    Oid funcid;              /* PG_PROC OID of the function */
    Oid funcresulttype;      /* PG_TYPE OID of result value */
    int32 funcresulttype_orig; /* PG_TYPE OID of original result value */
    bool funcretset;         /* true if function returns set */
    /* true if variadic arguments have been  combined into an array last argument */
    bool funcvariadic;     
    CoercionForm funcformat; /* how to display this function call */
    Oid funccollid;          /* OID of collation of result */
    Oid inputcollid;         /* OID of collation that function should use */
    uint32 funcflags;
    char* fmtstr;            /* fmt string */
    char* nlsfmtstr;         /* nls fmt string */
    List* args;              /* arguments to the function */  
    int location;            /* token location, or -1 if unknown */
    Oid refSynOid;           /* PG_SYNONYM OID of the referenced synonym */
} FuncExpr;

/*
 * NamedArgExpr - a named argument of a function
 *
 * This node type can only appear in the args list of a FuncCall or FuncExpr
 * node.  We support pure positional call notation (no named arguments),
 * named notation (all arguments are named), and mixed notation (unnamed
 * arguments followed by named ones).
 *
 * Parse analysis sets argnumber to the positional index of the argument,
 * but doesn't rearrange the argument list.
 *
 * The planner will convert argument lists to pure positional notation
 * during expression preprocessing, so execution never sees a NamedArgExpr.
 */
typedef struct NamedArgExpr {
    Expr xpr;
    Expr* arg;     /* the argument expression */
    char* name;    /* the name */
    int argnumber; /* argument's number in positional notation */
    int location;  /* argument name location, or -1 if unknown */
} NamedArgExpr;

/*
 * OpExpr - expression node for an operator invocation
 *
 * Semantically, this is essentially the same as a function call.
 *
 * Note that opfuncid is not necessarily filled in immediately on creation
 * of the node.  The planner makes sure it is valid before passing the node
 * tree to the executor, but during parsing/planning opfuncid can be 0.
 */
typedef struct OpExpr {
    Expr xpr;
    Oid opno;         /* PG_OPERATOR OID of the operator */
    Oid opfuncid;     /* PG_PROC OID of underlying function */
    Oid opresulttype; /* PG_TYPE OID of result value */
    bool opretset;    /* true if operator returns set */
    Oid opcollid;     /* OID of collation of result */
    Oid inputcollid;  /* OID of collation that operator should use */
    List* args;       /* arguments to the operator (1 or 2) */
    int location;     /* token location, or -1 if unknown */
} OpExpr;

/*
 * DistinctExpr - expression node for "x IS DISTINCT FROM y"
 *
 * Except for the nodetag, this is represented identically to an OpExpr
 * referencing the "=" operator for x and y.
 * We use "=", not the more obvious "<>", because more datatypes have "="
 * than "<>".  This means the executor must invert the operator result.
 * Note that the operator function won't be called at all if either input
 * is NULL, since then the result can be determined directly.
 */
typedef OpExpr DistinctExpr;

/*
 * NullIfExpr - a NULLIF expression
 *
 * Like DistinctExpr, this is represented the same as an OpExpr referencing
 * the "=" operator for x and y.
 */
typedef OpExpr NullIfExpr;

/*
 * ScalarArrayOpExpr - expression node for "scalar op ANY/ALL (array)"
 *
 * The operator must yield boolean.  It is applied to the left operand
 * and each element of the righthand array, and the results are combined
 * with OR or AND (for ANY or ALL respectively).  The node representation
 * is almost the same as for the underlying operator, but we need a useOr
 * flag to remember whether it's ANY or ALL, and we don't have to store
 * the result type (or the collation) because it must be boolean.
 *
 * A ScalarArrayOpExpr with a valid hashfuncid is evaluated during execution
 * by building a hash table containing the Const values from the rhs arg.
 * This table is probed during expression evaluation.  Only useOr=true
 * ScalarArrayOpExpr with Const arrays on the rhs can have the hashfuncid
 * field set. See convert_saop_to_hashed_saop().
 * by building a hash table containing the Const values from the RHS arg.
 * This table is probed during expression evaluation.  The planner will set
 * hashfuncid to the hash function which must be used to build and probe the
 * hash table.  The executor determines if it should use hash-based checks or
 * the more traditional means based on if the hashfuncid is set or not.
 *
 * When performing hashed NOT IN, the negfuncid will also be set to the
 * equality function which the hash table must use to build and probe the hash
 * table.  opno and opfuncid will remain set to the <> operator and its
 * corresponding function and won't be used during execution.  For
 * non-hashtable based NOT INs, negfuncid will be set to InvalidOid.  See
 * convert_saop_to_hashed_saop().
 */
typedef struct ScalarArrayOpExpr {
    Expr xpr;
    Oid opno;        /* PG_OPERATOR OID of the operator */
    Oid opfuncid;    /* PG_PROC OID of underlying function */
    Oid hashfuncid;  /* PG_PROC OID of hash func or InvalidOid */
    Oid negfuncid;   /* PG_PROC OID of negator of opfuncid function or InvalidOid.  See above */
    bool useOr;      /* true for ANY, false for ALL */
    Oid inputcollid; /* OID of collation that operator should use */
    List* args;      /* the scalar and array operands */
    int location;    /* token location, or -1 if unknown */
} ScalarArrayOpExpr;

/*
 * BoolExpr - expression node for the basic Boolean operators AND, OR, NOT
 *
 * Notice the arguments are given as a List.  For NOT, of course the list
 * must always have exactly one element.  For AND and OR, the executor can
 * handle any number of arguments.	The parser generally treats AND and OR
 * as binary and so it typically only produces two-element lists, but the
 * optimizer will flatten trees of AND and OR nodes to produce longer lists
 * when possible.  There are also a few special cases where more arguments
 * can appear before optimization.
 */
typedef enum BoolExprType { AND_EXPR, OR_EXPR, NOT_EXPR } BoolExprType;

typedef struct BoolExpr {
    Expr xpr;
    BoolExprType boolop;
    List* args;   /* arguments to this expression */
    int location; /* token location, or -1 if unknown */
} BoolExpr;

/*
 * SubLink
 *
 * A SubLink represents a subselect appearing in an expression, and in some
 * cases also the combining operator(s) just above it.	The subLinkType
 * indicates the form of the expression represented:
 *	EXISTS_SUBLINK		EXISTS(SELECT ...)
 *	ALL_SUBLINK			(lefthand) op ALL (SELECT ...)
 *	ANY_SUBLINK			(lefthand) op ANY (SELECT ...)
 *	ROWCOMPARE_SUBLINK	(lefthand) op (SELECT ...)
 *	EXPR_SUBLINK		(SELECT with single targetlist item ...)
 *	ARRAY_SUBLINK		ARRAY(SELECT with single targetlist item ...)
 *	CTE_SUBLINK			WITH query (never actually part of an expression)
 * For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the
 * same length as the subselect's targetlist.  ROWCOMPARE will *always* have
 * a list with more than one entry; if the subselect has just one target
 * then the parser will create an EXPR_SUBLINK instead (and any operator
 * above the subselect will be represented separately).  Note that both
 * ROWCOMPARE and EXPR require the subselect to deliver only one row.
 * ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean
 * results.  ALL and ANY combine the per-row results using AND and OR
 * semantics respectively.
 * ARRAY requires just one target column, and creates an array of the target
 * column's type using any number of rows resulting from the subselect.
 *
 * SubLink is classed as an Expr node, but it is not actually executable;
 * it must be replaced in the expression tree by a SubPlan node during
 * planning.
 *
 * NOTE: in the raw output of gram.y, testexpr contains just the raw form
 * of the lefthand expression (if any), and operName is the String name of
 * the combining operator.	Also, subselect is a raw parsetree.  During parse
 * analysis, the parser transforms testexpr into a complete boolean expression
 * that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the
 * output columns of the subselect.  And subselect is transformed to a Query.
 * This is the representation seen in saved rules and in the rewriter.
 *
 * In EXISTS, EXPR, and ARRAY SubLinks, testexpr and operName are unused and
 * are always null.
 *
 * The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used
 * in SubPlans generated for WITH subqueries.
 */
typedef enum SubLinkType {
    EXISTS_SUBLINK,
    ALL_SUBLINK,
    ANY_SUBLINK,
    ROWCOMPARE_SUBLINK,
    EXPR_SUBLINK,
    ARRAY_SUBLINK,
#ifdef USE_SPQ
    NOT_EXISTS_SUBLINK, /* spq uses NOT_EXIST_SUBLINK to implement correlated left anti semijoin. */
#endif
    CTE_SUBLINK /* for SubPlans only */
} SubLinkType;

typedef struct SubLink {
    Expr xpr;
    SubLinkType subLinkType; /* see above */
    Node* testexpr;          /* outer-query test for ALL/ANY/ROWCOMPARE */
    List* operName;          /* originally specified operator name */
    Node* subselect;         /* subselect as Query* or parsetree */
    int location;            /* token location, or -1 if unknown */
} SubLink;

/*
 * SubPlan - executable expression node for a subplan (sub-SELECT)
 *
 * The planner replaces SubLink nodes in expression trees with SubPlan
 * nodes after it has finished planning the subquery.  SubPlan references
 * a sub-plantree stored in the subplans list of the toplevel PlannedStmt.
 * (We avoid a direct link to make it easier to copy expression trees
 * without causing multiple processing of the subplan.)
 *
 * In an ordinary subplan, testexpr points to an executable expression
 * (OpExpr, an AND/OR tree of OpExprs, or RowCompareExpr) for the combining
 * operator(s); the left-hand arguments are the original lefthand expressions,
 * and the right-hand arguments are PARAM_EXEC Param nodes representing the
 * outputs of the sub-select.  (NOTE: runtime coercion functions may be
 * inserted as well.)  This is just the same expression tree as testexpr in
 * the original SubLink node, but the PARAM_SUBLINK nodes are replaced by
 * suitably numbered PARAM_EXEC nodes.
 *
 * If the sub-select becomes an initplan rather than a subplan, the executable
 * expression is part of the outer plan's expression tree (and the SubPlan
 * node itself is not, but rather is found in the outer plan's initPlan
 * list).  In this case testexpr is NULL to avoid duplication.
 *
 * The planner also derives lists of the values that need to be passed into
 * and out of the subplan.	Input values are represented as a list "args" of
 * expressions to be evaluated in the outer-query context (currently these
 * args are always just Vars, but in principle they could be any expression).
 * The values are assigned to the global PARAM_EXEC params indexed by parParam
 * (the parParam and args lists must have the same ordering).  setParam is a
 * list of the PARAM_EXEC params that are computed by the sub-select, if it
 * is an initplan; they are listed in order by sub-select output column
 * position.  (parParam and setParam are integer Lists, not Bitmapsets,
 * because their ordering is significant.)
 *
 * Also, the planner computes startup and per-call costs for use of the
 * SubPlan.  Note that these include the cost of the subquery proper,
 * evaluation of the testexpr if any, and any hashtable management overhead.
 */
typedef struct SubPlan {
    Expr xpr;
    /* Fields copied from original SubLink: */
    SubLinkType subLinkType; /* see above */
    /* The combining operators, transformed to an executable expression: */
    Node* testexpr; /* OpExpr or RowCompareExpr expression tree */
    List* paramIds; /* IDs of Params embedded in the above */
    /* Identification of the Plan tree to use: */
    int plan_id; /* Index (from 1) in PlannedStmt.subplans */
    /* Identification of the SubPlan for EXPLAIN and debugging purposes: */
    char* plan_name; /* A name assigned during planning */
    /* Extra data useful for determining subplan's output type: */
    Oid firstColType;      /* Type of first column of subplan result */
    int32 firstColTypmod;  /* Typmod of first column of subplan result */
    Oid firstColCollation; /* Collation of first column of subplan result */
    /* Information about execution strategy: */
    /* TRUE to store subselect output in a hash table (implies we are doing "IN") */
    bool useHashTable;
    /* TRUE if it's okay to return FALSE when the spec result is UNKNOWN; this allows much simpler handling of null values */
    bool unknownEqFalse; 
    /* Information for passing params into and out of the subselect: */
    /* setParam and parParam are lists of integers (param IDs) */
    List* setParam; /* initplan subqueries have to set these Params for parent plan */
    List* parParam; /* indices of input Params from parent plan */
    List* args;     /* exprs to pass as parParam values */
    /* Estimated execution costs: */
    Cost startup_cost;  /* one-time setup cost */
    Cost per_call_cost; /* cost for each subplan evaluation */
#ifdef USE_SPQ
    bool is_initplan; /* SPQ: Is the subplan implemented as an initplan? */
    bool is_multirow; /* SPQ: May the subplan return more than one row? */
#endif
} SubPlan;

/*
 * AlternativeSubPlan - expression node for a choice among SubPlans
 *
 * The subplans are given as a List so that the node definition need not
 * change if there's ever more than two alternatives.  For the moment,
 * though, there are always exactly two; and the first one is the fast-start
 * plan.
 */
typedef struct AlternativeSubPlan {
    Expr xpr;
    List* subplans; /* SubPlan(s) with equivalent results */
} AlternativeSubPlan;

/* ----------------
 * FieldSelect
 *
 * FieldSelect represents the operation of extracting one field from a tuple
 * value.  At runtime, the input expression is expected to yield a rowtype
 * Datum.  The specified field number is extracted and returned as a Datum.
 * ----------------
 */
typedef struct FieldSelect {
    Expr xpr;
    Expr* arg;           /* input expression */
    AttrNumber fieldnum; /* attribute number of field to extract */
    Oid resulttype;      /* type of the field (result type of this
                          * node) */
    int32 resulttypmod;  /* output typmod (usually -1) */
    Oid resultcollid;    /* OID of collation of the field */
} FieldSelect;

/* ----------------
 * FieldStore
 *
 * FieldStore represents the operation of modifying one field in a tuple
 * value, yielding a new tuple value (the input is not touched!).  Like
 * the assign case of ArrayRef, this is used to implement UPDATE of a
 * portion of a column.
 *
 * A single FieldStore can actually represent updates of several different
 * fields.	The parser only generates FieldStores with single-element lists,
 * but the planner will collapse multiple updates of the same base column
 * into one FieldStore.
 * ----------------
 */
typedef struct FieldStore {
    Expr xpr;
    Expr* arg;       /* input tuple value */
    List* newvals;   /* new value(s) for field(s) */
    List* fieldnums; /* integer list of field attnums */
    Oid resulttype;  /* type of result (same as type of arg) */
                     /* Like RowExpr, we deliberately omit a typmod and collation here */
} FieldStore;

/* ----------------
 * RelabelType
 *
 * RelabelType represents a "dummy" type coercion between two binary-
 * compatible datatypes, such as reinterpreting the result of an OID
 * expression as an int4.  It is a no-op at runtime; we only need it
 * to provide a place to store the correct type to be attributed to
 * the expression result during type resolution.  (We can't get away
 * with just overwriting the type field of the input expression node,
 * so we need a separate node to show the coercion's result type.)
 * ----------------
 */
typedef struct RelabelType {
    Expr xpr;
    Expr* arg;                  /* input expression */
    Oid resulttype;             /* output type of coercion expression */
    int32 resulttypmod;         /* output typmod (usually -1) */
    Oid resultcollid;           /* OID of collation, or InvalidOid if none */
    CoercionForm relabelformat; /* how to display this node */
    int location;               /* token location, or -1 if unknown */
} RelabelType;

/* ----------------
 * CoerceViaIO
 *
 * CoerceViaIO represents a type coercion between two types whose textual
 * representations are compatible, implemented by invoking the source type's
 * typoutput function then the destination type's typinput function.
 * ----------------
 */
typedef struct CoerceViaIO {
    Expr xpr;
    Expr* arg;      /* input expression */
    char* fmtstr;
    char* nlsfmtstr;
    Oid resulttype; /* output type of coercion */
    /* output typmod is not stored, but is presumed -1 */
    Oid resultcollid;          /* OID of collation, or InvalidOid if none */
    CoercionForm coerceformat; /* how to display this node */
    int location;              /* token location, or -1 if unknown */
} CoerceViaIO;

/* ----------------
 * ArrayCoerceExpr
 *
 * ArrayCoerceExpr represents a type coercion from one array type to another,
 * which is implemented by applying the indicated element-type coercion
 * function to each element of the source array.  If elemfuncid is InvalidOid
 * then the element types are binary-compatible, but the coercion still
 * requires some effort (we have to fix the element type ID stored in the
 * array header).
 * ----------------
 */
typedef struct ArrayCoerceExpr {
    Expr xpr;
    Expr* arg;                 /* input expression (yields an array) */
    char* fmtstr;              /* fmr string */
    char* nlsfmtstr;           /*  nls fmt string */
    Oid elemfuncid;            /* OID of element coercion function, or 0 */
    Oid resulttype;            /* output type of coercion (an array type) */
    int32 resulttypmod;        /* output typmod (also element typmod) */
    Oid resultcollid;          /* OID of collation, or InvalidOid if none */
    bool isExplicit;           /* conversion semantics flag to pass to func */
    CoercionForm coerceformat; /* how to display this node */
    int location;              /* token location, or -1 if unknown */
} ArrayCoerceExpr;

/* ----------------
 * ConvertRowtypeExpr
 *
 * ConvertRowtypeExpr represents a type coercion from one composite type
 * to another, where the source type is guaranteed to contain all the columns
 * needed for the destination type plus possibly others; the columns need not
 * be in the same positions, but are matched up by name.  This is primarily
 * used to convert a whole-row value of an inheritance child table into a
 * valid whole-row value of its parent table's rowtype.
 * ----------------
 */
typedef struct ConvertRowtypeExpr {
    Expr xpr;
    Expr* arg;      /* input expression */
    Oid resulttype; /* output type (always a composite type) */
    /* Like RowExpr, we deliberately omit a typmod and collation here */
    CoercionForm convertformat; /* how to display this node */
    int location;               /* token location, or -1 if unknown */
} ConvertRowtypeExpr;

/* ----------
 * CollateExpr - COLLATE
 *
 * The planner replaces CollateExpr with RelabelType during expression
 * preprocessing, so execution never sees a CollateExpr.
 * ----------
 */
typedef struct CollateExpr {
    Expr xpr;
    Expr* arg;    /* input expression */
    Oid collOid;  /* collation's OID */
    int location; /* token location, or -1 if unknown */
} CollateExpr;

/* ----------
 * CaseExpr - a CASE expression
 *
 * We support two distinct forms of CASE expression:
 *		CASE WHEN boolexpr THEN expr [ WHEN boolexpr THEN expr ... ]
 *		CASE testexpr WHEN compexpr THEN expr [ WHEN compexpr THEN expr ... ]
 * These are distinguishable by the "arg" field being NULL in the first case
 * and the testexpr in the second case.
 *
 * In the raw grammar output for the second form, the condition expressions
 * of the WHEN clauses are just the comparison values.	Parse analysis
 * converts these to valid boolean expressions of the form
 *		CaseTestExpr '=' compexpr
 * where the CaseTestExpr node is a placeholder that emits the correct
 * value at runtime.  This structure is used so that the testexpr need be
 * evaluated only once.  Note that after parse analysis, the condition
 * expressions always yield boolean.
 *
 * Note: we can test whether a CaseExpr has been through parse analysis
 * yet by checking whether casetype is InvalidOid or not.
 * ----------
 */
typedef struct CaseExpr {
    Expr xpr;
    Oid casetype;    /* type of expression result */
    Oid casecollid;  /* OID of collation, or InvalidOid if none */
    Expr* arg;       /* implicit equality comparison argument */
    List* args;      /* the arguments (list of WHEN clauses) */
    Expr* defresult; /* the default result (ELSE clause) */
    int location;    /* token location, or -1 if unknown */
    bool fromDecode; /* whether is parsed from decode expr, no need to (de-)serialize */
} CaseExpr;

/*
 * CaseWhen - one arm of a CASE expression
 */
typedef struct CaseWhen {
    Expr xpr;
    Expr* expr;   /* condition expression */
    Expr* result; /* substitution result */
    int location; /* token location, or -1 if unknown */
} CaseWhen;

/*
 * Placeholder node for the test value to be processed by a CASE expression.
 * This is effectively like a Param, but can be implemented more simply
 * since we need only one replacement value at a time.
 *
 * We also use this in nested UPDATE expressions.
 * See transformAssignmentIndirection().
 */
typedef struct CaseTestExpr {
    Expr xpr;
    Oid typeId;    /* type for substituted value */
    int32 typeMod; /* typemod for substituted value */
    Oid collation; /* collation for the substituted value */
} CaseTestExpr;

/*
 * ArrayExpr - an ARRAY[] expression
 *
 * Note: if multidims is false, the constituent expressions all yield the
 * scalar type identified by element_typeid.  If multidims is true, the
 * constituent expressions all yield arrays of element_typeid (ie, the same
 * type as array_typeid); at runtime we must check for compatible subscripts.
 */
typedef struct ArrayExpr {
    Expr xpr;
    Oid array_typeid;   /* type of expression result */
    Oid array_collid;   /* OID of collation, or InvalidOid if none */
    Oid element_typeid; /* common type of array elements */
    List* elements;     /* the array elements or sub-arrays */
    bool multidims;     /* true if elements are sub-arrays */
    int location;       /* token location, or -1 if unknown */
} ArrayExpr;

/*
 * RowExpr - a ROW() expression
 *
 * Note: the list of fields must have a one-for-one correspondence with
 * physical fields of the associated rowtype, although it is okay for it
 * to be shorter than the rowtype.	That is, the N'th list element must
 * match up with the N'th physical field.  When the N'th physical field
 * is a dropped column (attisdropped) then the N'th list element can just
 * be a NULL constant.	(This case can only occur for named composite types,
 * not RECORD types, since those are built from the RowExpr itself rather
 * than vice versa.)  It is important not to assume that length(args) is
 * the same as the number of columns logically present in the rowtype.
 *
 * colnames provides field names in cases where the names can't easily be
 * obtained otherwise.	Names *must* be provided if row_typeid is RECORDOID.
 * If row_typeid identifies a known composite type, colnames can be NIL to
 * indicate the type's cataloged field names apply.  Note that colnames can
 * be non-NIL even for a composite type, and typically is when the RowExpr
 * was created by expanding a whole-row Var.  This is so that we can retain
 * the column alias names of the RTE that the Var referenced (which would
 * otherwise be very difficult to extract from the parsetree).	Like the
 * args list, colnames is one-for-one with physical fields of the rowtype.
 */
typedef struct RowExpr {
    Expr xpr;
    List* args;     /* the fields */
    Oid row_typeid; /* RECORDOID or a composite type's ID */

    /*
     * Note: we deliberately do NOT store a typmod.  Although a typmod will be
     * associated with specific RECORD types at runtime, it will differ for
     * different backends, and so cannot safely be stored in stored
     * parsetrees.	We must assume typmod -1 for a RowExpr node.
     *
     * We don't need to store a collation either.  The result type is
     * necessarily composite, and composite types never have a collation.
     */
    CoercionForm row_format; /* how to display this node */
    List* colnames;          /* list of String, or NIL */
    int location;            /* token location, or -1 if unknown */
} RowExpr;

/*
 * RowCompareExpr - row-wise comparison, such as (a, b) <= (1, 2)
 *
 * We support row comparison for any operator that can be determined to
 * act like =, <>, <, <=, >, or >= (we determine this by looking for the
 * operator in btree opfamilies).  Note that the same operator name might
 * map to a different operator for each pair of row elements, since the
 * element datatypes can vary.
 *
 * A RowCompareExpr node is only generated for the < <= > >= cases;
 * the = and <> cases are translated to simple AND or OR combinations
 * of the pairwise comparisons.  However, we include = and <> in the
 * RowCompareType enum for the convenience of parser logic.
 */
typedef enum RowCompareType {
    /* Values of this enum are chosen to match btree strategy numbers */
    ROWCOMPARE_LT = 1, /* BTLessStrategyNumber */
    ROWCOMPARE_LE = 2, /* BTLessEqualStrategyNumber */
    ROWCOMPARE_EQ = 3, /* BTEqualStrategyNumber */
    ROWCOMPARE_GE = 4, /* BTGreaterEqualStrategyNumber */
    ROWCOMPARE_GT = 5, /* BTGreaterStrategyNumber */
    ROWCOMPARE_NE = 6  /* no such btree strategy */
} RowCompareType;

typedef struct RowCompareExpr {
    Expr xpr;
    RowCompareType rctype; /* LT LE GE or GT, never EQ or NE */
    List* opnos;           /* OID list of pairwise comparison ops */
    List* opfamilies;      /* OID list of containing operator families */
    List* inputcollids;    /* OID list of collations for comparisons */
    List* largs;           /* the left-hand input arguments */
    List* rargs;           /* the right-hand input arguments */
} RowCompareExpr;

/*
 * CoalesceExpr - a COALESCE expression
 */
typedef struct CoalesceExpr {
    Expr xpr;
    Oid coalescetype;   /* type of expression result */
    Oid coalescecollid; /* OID of collation, or InvalidOid if none */
    List* args;         /* the arguments */
    int location;       /* token location, or -1 if unknown */
    bool isnvl;         /* is CoalesceExpr NVL ? */
} CoalesceExpr;

/*
 * MinMaxExpr - a GREATEST or LEAST function
 */
typedef enum MinMaxOp { IS_GREATEST, IS_LEAST } MinMaxOp;

typedef struct MinMaxExpr {
    Expr xpr;
    Oid minmaxtype;   /* common type of arguments and result */
    Oid minmaxcollid; /* OID of collation of result */
    Oid inputcollid;  /* OID of collation that function should use */
    MinMaxOp op;      /* function to execute */
    List* args;       /* the arguments */
    int location;     /* token location, or -1 if unknown */
    Oid cmptype;       /* the comparison type */
    List* cmpargs; /* the comparison arguments */
} MinMaxExpr;

/*
 * XmlExpr - various SQL/XML functions requiring special grammar productions
 *
 * 'name' carries the "NAME foo" argument (already XML-escaped).
 * 'named_args' and 'arg_names' represent an xml_attribute list.
 * 'args' carries all other arguments.
 *
 * Note: result type/typmod/collation are not stored, but can be deduced
 * from the XmlExprOp.	The type/typmod fields are just used for display
 * purposes, and are NOT necessarily the true result type of the node.
 * (We also use type == InvalidOid to mark a not-yet-parse-analyzed XmlExpr.)
 */
typedef enum XmlExprOp {
    IS_XMLCONCAT,    /* XMLCONCAT(args) */
    IS_XMLELEMENT,   /* XMLELEMENT(name, xml_attributes, args) */
    IS_XMLFOREST,    /* XMLFOREST(xml_attributes) */
    IS_XMLPARSE,     /* XMLPARSE(text, is_doc, preserve_ws) */
    IS_XMLPI,        /* XMLPI(name [, args]) */
    IS_XMLROOT,      /* XMLROOT(xml, version, standalone) */
    IS_XMLSERIALIZE, /* XMLSERIALIZE(is_document, xmlval) */
    IS_DOCUMENT      /* xmlval IS DOCUMENT */
} XmlExprOp;

typedef enum { XMLOPTION_DOCUMENT, XMLOPTION_CONTENT } XmlOptionType;

typedef struct XmlExpr {
    Expr xpr;
    XmlExprOp op;            /* xml function ID */
    char* name;              /* name in xml(NAME foo ...) syntaxes */
    List* named_args;        /* non-XML expressions for xml_attributes */
    List* arg_names;         /* parallel list of Value strings */
    List* args;              /* list of expressions */
    XmlOptionType xmloption; /* DOCUMENT or CONTENT */
    Oid type;                /* target type/typmod for XMLSERIALIZE */
    int32 typmod;
    int location; /* token location, or -1 if unknown */
} XmlExpr;

typedef struct PrefixKey {
    Expr xpr;
    Expr* arg; /* should be a ColumnRef or Var */
    int length; /* prefix length */
} PrefixKey;

/* ----------------
 * NullTest
 *
 * NullTest represents the operation of testing a value for NULLness.
 * The appropriate test is performed and returned as a boolean Datum.
 *
 * When argisrow is false, this simply represents a test for the null value.
 *
 * When argisrow is true, the input expression must yield a rowtype, and
 * the node implements "row IS [NOT] NULL" per the SQL standard.  This
 * includes checking individual fields for NULLness when the row datum
 * itself isn't NULL.
 *
 * NOTE: the combination of a rowtype input and argisrow==false does NOT
 * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
 * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
 * ----------------
 */
typedef enum NullTestType { IS_NULL, IS_NOT_NULL } NullTestType;

typedef struct NullTest {
    Expr xpr;
    Expr* arg;                 /* input expression */
    NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
    bool argisrow;             /* T to perform field-by-field null checks */
} NullTest;

/* ----------------
 * NanTest
 *
 * NanTest represents the operation of testing a value for Nan.
 * The appropriate test is performed and returned as a boolean Datum.
 * ----------------
 */
typedef enum NanTestType { IS_NAN, IS_NOT_NAN } NanTestType;

typedef struct NanTest {
    Expr xpr;
    Expr* arg;                 /* input expression */
    NanTestType nantesttype;   /* IS NAN, IS NOT NAN */
} NanTest;

/* ----------------
 * InfiniteTest
 *
 * InfiniteTest represents the operation of testing a value for Infinite.
 * The appropriate test is performed and returned as a boolean Datum.
 * ----------------
 */
typedef enum InfiniteTestType { IS_INFINITE, IS_NOT_INFINITE } InfiniteTestType;

typedef struct InfiniteTest {
    Expr xpr;
    Expr* arg;                 /* input expression */
    InfiniteTestType infinitetesttype;   /* IS INFINITE, IS NOT INFINITE */
} InfiniteTest;

/*
 * BooleanTest
 *
 * BooleanTest represents the operation of determining whether a boolean
 * is TRUE, FALSE, or UNKNOWN (ie, NULL).  All six meaningful combinations
 * are supported.  Note that a NULL input does *not* cause a NULL result.
 * The appropriate test is performed and returned as a boolean Datum.
 */
typedef enum BoolTestType { IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN } BoolTestType;

typedef struct BooleanTest {
    Expr xpr;
    Expr* arg;                 /* input expression */
    BoolTestType booltesttype; /* test type */
} BooleanTest;

/* HashFilter indicate that filter tuple using hash */
typedef struct HashFilter {
    Expr xpr;
    List* arg;      /* input expression */
    List* typeOids; /* type oid list of var for filter */
    List* nodeList; /* Node indices where data is located */
                    // uint2      *bucketMap;
} HashFilter;

/*
 * EstSPNode
 *
 * For some expression, we can't estimate them though vars under them. Therefore,
 * we should keep them and get the vars under them to get an overall estimation.
 */
typedef struct EstSPNode {
    Expr xpr;
    Node* expr;
    List* varlist;
} EstSPNode;

/*
 * CoerceToDomain
 *
 * CoerceToDomain represents the operation of coercing a value to a domain
 * type.  At runtime (and not before) the precise set of constraints to be
 * checked will be determined.	If the value passes, it is returned as the
 * result; if not, an error is raised.	Note that this is equivalent to
 * RelabelType in the scenario where no constraints are applied.
 */
typedef struct CoerceToDomain {
    Expr xpr;
    Expr* arg;                   /* input expression */
    Oid resulttype;              /* domain type ID (result type) */
    int32 resulttypmod;          /* output typmod (currently always -1) */
    Oid resultcollid;            /* OID of collation, or InvalidOid if none */
    CoercionForm coercionformat; /* how to display this node */
    int location;                /* token location, or -1 if unknown */
} CoerceToDomain;

/*
 * Placeholder node for the value to be processed by a domain's check
 * constraint.	This is effectively like a Param, but can be implemented more
 * simply since we need only one replacement value at a time.
 *
 * Note: the typeId/typeMod/collation will be set from the domain's base type,
 * not the domain itself.  This is because we shouldn't consider the value
 * to be a member of the domain if we haven't yet checked its constraints.
 */
typedef struct CoerceToDomainValue {
    Expr xpr;
    Oid typeId;    /* type for substituted value */
    int32 typeMod; /* typemod for substituted value */
    Oid collation; /* collation for the substituted value */
    int location;  /* token location, or -1 if unknown */
} CoerceToDomainValue;

/*
 * Placeholder node for a DEFAULT marker in an INSERT or UPDATE command.
 *
 * This is not an executable expression: it must be replaced by the actual
 * column default expression during rewriting.	But it is convenient to
 * treat it as an expression node during parsing and rewriting.
 */
typedef struct SetToDefault {
    Expr xpr;
    Oid typeId;    /* type for substituted value */
    int32 typeMod; /* typemod for substituted value */
    Oid collation; /* collation for the substituted value */
    int location;  /* token location, or -1 if unknown */
    bool lrchild_unknown;
} SetToDefault;

/* value expressions (changed for client_logic feature) */
typedef struct ExprWithComma {
    NodeTag type;
    Expr *xpr;
    int comma_before_loc;
} ExprWithComma;

/*
 * Node representing [WHERE] CURRENT OF cursor_name
 *
 * CURRENT OF is a bit like a Var, in that it carries the rangetable index
 * of the target relation being constrained; this aids placing the expression
 * correctly during planning.  We can assume however that its "levelsup" is
 * always zero, due to the syntactic constraints on where it can appear.
 *
 * The referenced cursor can be represented either as a hardwired string
 * or as a reference to a run-time parameter of type REFCURSOR.  The latter
 * case is for the convenience of plpgsql.
 */
typedef struct CurrentOfExpr {
    Expr xpr;
    Index cvarno;      /* RT index of target relation */
    char* cursor_name; /* name of referenced cursor, or NULL */
    int cursor_param;  /* refcursor parameter number, or 0 */
} CurrentOfExpr;

/* SetVariableExpr used for getting guc variable's value */
typedef struct {
    Expr xpr;
    char* name;
    Expr* value;
    bool is_session;    /* true is session, only used in B compability */
    bool is_global;     /* true is global, only used in B compability */
} SetVariableExpr;

/* --------------------
 * TargetEntry -
 *	   a target entry (used in query target lists)
 *
 * Strictly speaking, a TargetEntry isn't an expression node (since it can't
 * be evaluated by ExecEvalExpr).  But we treat it as one anyway, since in
 * very many places it's convenient to process a whole query targetlist as a
 * single expression tree.
 *
 * In a SELECT's targetlist, resno should always be equal to the item's
 * ordinal position (counting from 1).	However, in an INSERT or UPDATE
 * targetlist, resno represents the attribute number of the destination
 * column for the item; so there may be missing or out-of-order resnos.
 * It is even legal to have duplicated resnos; consider
 *		UPDATE table SET arraycol[1] = ..., arraycol[2] = ..., ...
 * The two meanings come together in the executor, because the planner
 * transforms INSERT/UPDATE tlists into a normalized form with exactly
 * one entry for each column of the destination table.	Before that's
 * happened, however, it is risky to assume that resno == position.
 * Generally get_tle_by_resno() should be used rather than list_nth()
 * to fetch tlist entries by resno, and only in SELECT should you assume
 * that resno is a unique identifier.
 *
 * resname is required to represent the correct column name in non-resjunk
 * entries of top-level SELECT targetlists, since it will be used as the
 * column title sent to the frontend.  In most other contexts it is only
 * a debugging aid, and may be wrong or even NULL.	(In particular, it may
 * be wrong in a tlist from a stored rule, if the referenced column has been
 * renamed by ALTER TABLE since the rule was made.	Also, the planner tends
 * to store NULL rather than look up a valid name for tlist entries in
 * non-toplevel plan nodes.)  In resjunk entries, resname should be either
 * a specific system-generated name (such as "ctid") or NULL; anything else
 * risks confusing ExecGetJunkAttribute!
 *
 * ressortgroupref is used in the representation of ORDER BY, GROUP BY, and
 * DISTINCT items.	Targetlist entries with ressortgroupref=0 are not
 * sort/group items.  If ressortgroupref>0, then this item is an ORDER BY,
 * GROUP BY, and/or DISTINCT target value.	No two entries in a targetlist
 * may have the same nonzero ressortgroupref --- but there is no particular
 * meaning to the nonzero values, except as tags.  (For example, one must
 * not assume that lower ressortgroupref means a more significant sort key.)
 * The order of the associated SortGroupClause lists determine the semantics.
 *
 * resorigtbl/resorigcol identify the source of the column, if it is a
 * simple reference to a column of a base table (or view).	If it is not
 * a simple reference, these fields are zeroes.
 *
 * If resjunk is true then the column is a working column (such as a sort key)
 * that should be removed from the final output of the query.  Resjunk columns
 * must have resnos that cannot duplicate any regular column's resno.  Also
 * note that there are places that assume resjunk columns come after non-junk
 * columns.
 * --------------------
 */
typedef struct TargetEntry {
    Expr xpr;
    Expr* expr;            /* expression to evaluate */
    AttrNumber resno;      /* attribute number (see notes above) */
    char* resname;         /* name of the column (could be NULL) */
    Index ressortgroupref; /* nonzero if referenced by a sort/group
                            * clause */
    Oid resorigtbl;        /* OID of column's source table */
    AttrNumber resorigcol; /* column's number in source table */
    bool resjunk;          /* set to true to eliminate the attribute from
                            * final target list */
    Index rtindex;         /* used when multiple modifying. It indicates the resultRelation 
                            * to which this TLE belongs. */
    bool isStartWithPseudo; 
} TargetEntry;

/* mainly support Start with */
typedef struct PseudoTargetEntry {
    NodeTag      type;
    TargetEntry *tle;
    TargetEntry *srctle;
} PseudoTargetEntry;

/* ----------------------------------------------------------------
 *					node types for join trees
 *
 * The leaves of a join tree structure are RangeTblRef nodes.  Above
 * these, JoinExpr nodes can appear to denote a specific kind of join
 * or qualified join.  Also, FromExpr nodes can appear to denote an
 * ordinary cross-product join ("FROM foo, bar, baz WHERE ...").
 * FromExpr is like a JoinExpr of jointype JOIN_INNER, except that it
 * may have any number of child nodes, not just two.
 *
 * NOTE: the top level of a Query's jointree is always a FromExpr.
 * Even if the jointree contains no rels, there will be a FromExpr.
 *
 * NOTE: the qualification expressions present in JoinExpr nodes are
 * *in addition to* the query's main WHERE clause, which appears as the
 * qual of the top-level FromExpr.	The reason for associating quals with
 * specific nodes in the jointree is that the position of a qual is critical
 * when outer joins are present.  (If we enforce a qual too soon or too late,
 * that may cause the outer join to produce the wrong set of NULL-extended
 * rows.)  If all joins are inner joins then all the qual positions are
 * semantically interchangeable.
 *
 * NOTE: in the raw output of gram.y, a join tree contains RangeVar,
 * RangeSubselect, and RangeFunction nodes, which are all replaced by
 * RangeTblRef nodes during the parse analysis phase.  Also, the top-level
 * FromExpr is added during parse analysis; the grammar regards FROM and
 * WHERE as separate.
 * ----------------------------------------------------------------
 */

/*
 * RangeTblRef - reference to an entry in the query's rangetable
 *
 * We could use direct pointers to the RT entries and skip having these
 * nodes, but multiple pointers to the same node in a querytree cause
 * lots of headaches, so it seems better to store an index into the RT.
 */
typedef struct RangeTblRef {
    NodeTag type;
    int rtindex;
} RangeTblRef;

/* ----------
 * JoinExpr - for SQL JOIN expressions
 *
 * isNatural, usingClause, and quals are interdependent.  The user can write
 * only one of NATURAL, USING(), or ON() (this is enforced by the grammar).
 * If he writes NATURAL then parse analysis generates the equivalent USING()
 * list, and from that fills in "quals" with the right equality comparisons.
 * If he writes USING() then "quals" is filled with equality comparisons.
 * If he writes ON() then only "quals" is set.	Note that NATURAL/USING
 * are not equivalent to ON() since they also affect the output column list.
 *
 * alias is an Alias node representing the AS alias-clause attached to the
 * join expression, or NULL if no clause.  NB: presence or absence of the
 * alias has a critical impact on semantics, because a join with an alias
 * restricts visibility of the tables/columns inside it.
 *
 * During parse analysis, an RTE is created for the Join, and its index
 * is filled into rtindex.	This RTE is present mainly so that Vars can
 * be created that refer to the outputs of the join.  The planner sometimes
 * generates JoinExprs internally; these can have rtindex = 0 if there are
 * no join alias variables referencing such joins.
 * ----------
 */
typedef struct JoinExpr {
    NodeTag type;
    JoinType jointype; /* type of join */
    bool isNatural;    /* Natural join? Will need to shape table */
    bool isAsof;       /* Asof join? */
    Node* larg;        /* left subtree */
    Node* rarg;        /* right subtree */
    List* usingClause; /* USING clause, if any (list of String) */
    Node* quals;       /* qualifiers on join, if any */
    Alias* alias;      /* user-written alias clause, if any */
    int rtindex;       /* RT index assigned for join, or 0 */
    bool is_straight_join; /* set true if straight_join */
    bool is_apply_join;    /* set true when on cross apply or outer apply join */
} JoinExpr;

/* ----------
 * FromExpr - represents a FROM ... WHERE ... construct
 *
 * This is both more flexible than a JoinExpr (it can have any number of
 * children, including zero) and less so --- we don't need to deal with
 * aliases and so on.  The output column set is implicitly just the union
 * of the outputs of the children.
 * ----------
 */
typedef struct FromExpr {
    NodeTag type;
    List* fromlist; /* List of join subtrees */
    Node* quals;    /* qualifiers on join, if any */
} FromExpr;

#ifdef PGXC
/* ----------
 * DistributionType - how to distribute the data
 *
 * ----------
 */
typedef enum DistributionType {
    DISTTYPE_REPLICATION, /* Replicated */
    DISTTYPE_HASH,        /* Hash partitioned */
    DISTTYPE_ROUNDROBIN,  /* Round Robin */
    DISTTYPE_MODULO,      /* Modulo partitioned */
    DISTTYPE_HIDETAG,     /* Use a hidden column as distribute column */
    DISTTYPE_LIST,        /* List */
    DISTTYPE_RANGE        /* Range */
} DistributionType;

typedef struct ListSliceDefState {
    NodeTag type;
    char* name;
    List* boundaries; /* list of boundary(multi-values) */
    char* datanode_name;
} ListSliceDefState;

typedef struct DistState {
    NodeTag type;
    /*
     * 'r' range slice
     * 'l' list slice
     */
    char strategy;
    /* list of slice definition, like: 
     * ListSliceDefState or RangePartitionDefState or RangePartitionStartEndDefState 
     */
    List* sliceList; 
    char* refTableName;
} DistState;

/* ----------
 * DistributeBy - represents a DISTRIBUTE BY clause in a CREATE TABLE statement
 *
 * ----------
 */
typedef struct DistributeBy {
    NodeTag type;
    DistributionType disttype; /* Distribution type */
    List* colname;             /* Distribution column name */
    DistState* distState;      /* Slice Definitions */
    Oid referenceoid;          /* table oid that slice references, InvalidOid if none */
} DistributeBy;

/* ----------
 * SubClusterType - type of subcluster used
 *
 * ----------
 */
typedef enum PGXCSubClusterType { SUBCLUSTER_NONE, SUBCLUSTER_NODE, SUBCLUSTER_GROUP } PGXCSubClusterType;

/* ----------
 * PGXCSubCluster - Subcluster on which a table can be created
 *
 * ----------
 */
typedef struct PGXCSubCluster {
    NodeTag type;
    PGXCSubClusterType clustertype; /* Subcluster type */
    List* members;                  /* List of nodes or groups */
} PGXCSubCluster;
#endif

typedef struct {
    NodeTag type;
    Oid relid;
    AttrNumber attno;
    char* relname;
    char* attname;

    bool indexcol;
    List* indexoids;
    bool indexpath;
} IndexVar;

typedef struct UpsertExpr {
    NodeTag type;
    UpsertAction upsertAction;    /* DO NOTHING or UPDATE? */

    /* DUPLICATE KEY UPDATE */
    List* updateTlist;        /* List of UPDATE TargetEntrys */
    List* exclRelTlist;       /* tlist of the 'EXCLUDED' pseudo relation */
    int exclRelIndex;         /* RT index of 'EXCLUDED' relation */
    Node* upsertWhere;        /* Qualifiers for upsert's update clause to check */
} UpsertExpr;

#ifdef USE_SPQ
/*
 * DMLActionExpr
 *
 * Represents the expression which introduces the action in a SplitUpdate statement
 */
typedef struct DMLActionExpr {
    Expr xpr;
} DMLActionExpr;
#endif

/*
 * DB4AI
 */
#define DB4AI_SNAPSHOT_VERSION_DELIMITER 1
#define DB4AI_SNAPSHOT_VERSION_SEPARATOR 2


#endif /* PRIMNODES_H */
